German Published Patent Application No. 38 31 196 A1 describes an electromagnetically actuated injection valve for fuel injection systems of mixture-compressing, spark-ignition internal combustion engines, in which injection valve a valve seat carrier and a valve needle are produced from the same material, for example chrome steel.
As the temperature of the fuel and of the interior of the internal combustion engine rises, the valve components, including the valve seat carrier and valve needle, assume an approximately equally high temperature. Since the valve seat carrier and the valve needle are produced from the same material, both valve components also have similar coefficients of thermal expansion; for example, the value .alpha. for chrome steel is approximately 16.times.10.sup.-6 K.sup.-1. As a result, during heating of the valve the longitudinal changes of the valve seat carrier and of the valve needle are similar. Consequently, the travel of the valve needle remains largely constant when temperature fluctuations occur in the internal combustion engine. When the valve is heated, a two-phase flow consisting of fuel and bubbles of gas is formed in the interior of the valve. This two-phase flow is disadvantageous to the extent that a reduction of the metered fuel inevitably occurs and thus a so-called leaning of the fuel/air mixture fed to the internal combustion engine occurs. A temperature increase in the interior of the internal combustion engine therefore has the consequence that when the same materials with identical coefficients of thermal expansion are used for the valve seat carrier and valve needle in the injection valve a reduction of the quantity of fuel delivered takes place.